This was a big no-no when I was growing up because of the growth plates in the body still maturing. My son just turned 14 and still hasn't hit puberty. He starts high school baseball this summer and they start workouts next monday. So has the opinion changed? My son says his fiends are starting to work out but the one's he mentions have already hit puberty.

I don't think that weightlifting is inherently bad for kids if its done properly, but it's often not. More importantly though, why should kids be in the gym in the first place? Let them play a variety of sports throughout the year (not specializing till late high school or even college) and they will get stronger, develop quality motor control, and become much more bad ass than you would ever see from sticking a kid in the gym at 10 years old. The gym should be a supplement to quality movement, and we generally don't need this supplement until high school at the earliest.